Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

Abstract

As promising candidates for plasma-facing materials, tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux. Radiation-produced defects, e.g. selfinterstitial atoms (SIAs) and vacancies (Vs), can induce the hardening and embrittlement of tungsten, meanwhile enhancing the retention of hydrogen isotopes and helium in tungsten. Reducing the grain size of materials to introduce a high density of defect sinks, e.g., grain boundaries (GBs) prevalent in nano-/ultrafine-crystalline materials, was demonstrated to be an effective approach for mitigating irradiation damage in tungsten. In this paper, we reviewed the theoretical advances in exploring radiation-resistance of nano-structured tungsten at across scales. It was concentrated on the results of molecular dynamics, molecular statics, and the object kinetic Monte Carlo simulations on the fundamental interaction of the radiationcreated Vs and SIAs with the GB. These mechanisms include GB-promoted V/SIA migration and SIA-V recombination, interstitial-emission induced annihilation, coupling of the V migration close to the GB with the SIA motion within the GB, and interstitial reflection by the locally dense GB structure. We proposed the remaining scientific issues on the defect-GB interactions at across scales and their relation to experimental observations. We prospected the possible trends for simulating the radiation damage accumulation and healing processes in nano-structured tungsten in terms of the development of the across-scale computational techniques and efficiency of the GB-enhanced tolerance of tungsten to irradiation under complex in-service conditions.

The Primary Irradiation Damage of Hydrogen-Accumulated Nickel: An Atomistic Study

“…The trend in the number of interstitials at the stabilization stage aligned with the Norgett–Robinson–Torrens (NRT) model [ 42 ]. All these results are consistent with observations from other studies [ 31 , 35 , 43 , 44 ].…”

“…The trend in the number of interstitials at the stabilization stage aligned with the Norgett-Robinson-Torrens (NRT) model [42]. All these results are consistent with observations from other studies [31,35,43,44]. To gain a comprehensive understanding of the influence of the PKA energy on the irradiation damage, the defect clustering and distributions at different moments are shown in Figure 5.…”

Phase-field microstructure-based effective thermal conductivity calculations in tungsten

“…Controlling the grain morphology during the fabrication process is a conventional way to improve the thermodynamics and mechanical properties of materials. Previous work has revealed that grain boundaries (GBs) can serve as sinks for defects to improve the irradiation resistance by reducing the formation energy of defects and the diffusion barrier at GBs [18][19][20][21], but also impede the heat transfer across them [22,23]. During the service, the combination of high temperature and high energy neutron irradiation can promote the GB migration and lead to grain growth [24][25][26][27], that is, the small grains with relatively large curvatures decrease their sizes, resulting in the increased overall average grain size.…”